What Was the Purpose of the Covenant Between Yahweh and the Hebrew

What was the purpose of the Covenant between Yahweh and the Hebrew people?

A) It established the promise of a Heavenly Kingdom on Earth.
B) It replaced an earlier moral contract between Yahweh and earlier prophets such as Amos and Isaiah.
C) It dealt with ethical matters but left other matters under the control of civil leaders.
D) It promised that if the Hebrews kept their solid faith in Yahweh, they would defeat all of their enemies.
E) It has failed, in later times, to adapt when social circumstances changed.